1. Field of the Invention
The invention generally relates to systems adapted for use in conducting in-flight wing wake section drag investigation employing traversing pitot and static probes, and more particularly to an improved system for use conducting wake investigations employing a single transducer and a pressure switching device for alternatively connecting pairs of pressure heads to the transducer in opposing relationships whereby measurements of pressure differentials for a wake are directly obtainable.
2. Description of the Prior Art
The prior art, of course, is replete with pressure sensing devices, such as pitot tubes and the like, employed in obtaining absolute pressure measurements for bodies in flight. Moreover, pitot-traverse techniques for detecting and measuring wake pressures for bodies in flight are well known. For example, see the Reports and Memorandums No. 1688 Brit. A.R.C., January 1963, and Use of a Pitot-static Probe for Determining Wing Section Drag In Flight at Mach Numbers From 0.5 to Approximately 1.0 NASA TMX-56025, July 1974, Lawrence C. Montoya, Merle A. Economu, and Ralph E. Cissell, obtainable through the NASA Flight Research Center, Edwards, Calif. 93523.
However, as can be fully appreciated by those familiar with techniques of this general nature, devices which provide absolute values for pressure measurements tend to lack the accuracy required in obtaining wing profile drag measurements for low values of dynamic and Reynolds Numbers. For example, improved accuracy is necessary if small airfoil performance differences, due to factors such as airfoil surface, ambient air turbulence or Reynolds Numbers are to be measured. The desired accuracy is necessary if aerodynamic efficiency is to be realized. Such efficiency has now become of primary concern by those attempting to reduce fuel consumption as well as designers attempting to select optimum airfoils for given missions.
It is, therefore, a general purpose of the instant invention to provide an improved pressure measuring system for use in conducting wake investigations for wings in flight, through a use of which data of enhanced accuracy and reliability is obtainable.